Correlative light and high-voltage electron microscopy of primary (9 + 0) cilia in cultured kidney epithelial cells

Roth, Karen E.; Davison, Edwin A.; Myers, Nicola; Rieder, Conly L.; Bowser, Samuel S.

doi:10.1017/s0424820100128420

Cited by 4 publications

(1 citation statement)

References 3 publications

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“…This raises the possibility that the 9ϩ0 axonemal structure we observe in the kinesin-IIblocked embryos may simply result from loss of an unstable central pair during fixation rather than from an inhibition of central pair formation. Although we can not formally rule out this possibility at this time, we favor the hypothesis that the cilia on K2.4-injected embryos never form a central pair because (a) not a single central MT was observed in K2.4-injected embryo axonemes and (b) several behavioral and morphological similarities are shared between the paralyzed cilia on living K2.4-injected blastulae before fixation and primary cilia in other cell types that are known to be 9ϩ0 (Menco, 1980;Poole et al, 1985;Roth et al, 1987Roth et al, , 1988Wheatley, 1995). Further work will be required to discriminate between inhibition of de novo assembly versus destabilization of central pair MTs in K2.4-injected embryos.…”

Section: Why Does Loss Of Kinesin-ii Function Results In Short and Paralyzed Cilia?mentioning

confidence: 80%

Heterotrimeric Kinesin-II Is Required for the Assembly of Motile 9+2 Ciliary Axonemes on Sea Urchin Embryos

Morris

Scholey

1997

The Journal of Cell Biology

168

139

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Heterotrimeric kinesin-II is a plus end– directed microtubule (MT) motor protein consisting of distinct heterodimerized motor subunits associated with an accessory subunit. To probe the intracellular transport functions of kinesin-II, we microinjected fertilized sea urchin eggs with an anti–kinesin-II monoclonal antibody, and we observed a dramatic inhibition of ciliogenesis at the blastula stage characterized by the assembly of short, paralyzed, 9+0 ciliary axonemes that lack central pair MTs. Control embryos show no such defect and form swimming blastulae with normal, motile, 9+2 cilia that contain kinesin-II as detected by Western blotting. Injection of anti–kinesin-II into one blastomere of a two-cell embryo leads to the development of chimeric blastulae covered on one side with short, paralyzed cilia, and on the other with normal, beating cilia. We observed a unimodal length distribution of short cilia on anti–kinesin-II–injected embryos corresponding to the first mode of the trimodal distribution of ciliary lengths observed for control embryos. This short mode may represent a default ciliary assembly intermediate. We hypothesize that kinesin-II functions during ciliogenesis to deliver ciliary components that are required for elongation of the assembly intermediate and for formation of stable central pair MTs. Thus, kinesin-II plays a critical role in embryonic development by supporting the maturation of nascent cilia to generate long motile organelles capable of producing the propulsive forces required for swimming and feeding.

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Section: Why Does Loss Of Kinesin-ii Function Results In Short and Paralyzed Cilia?mentioning

confidence: 80%

Heterotrimeric Kinesin-II Is Required for the Assembly of Motile 9+2 Ciliary Axonemes on Sea Urchin Embryos

Morris

Scholey

1997

The Journal of Cell Biology

168

139

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Directed movements of ciliary and flagellar membrane components: A review

Bloodgood

1992

Biology of the Cell

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The ability to rapidly translocate polystyrene microspheres attached to the surface of a plasma membrane domain reflects a unique form of cellular force transduction occurring in association with the plasma membrane of microtubule based cell extensions. This unusual form of cell motility can be utilized by protistan organisms for whole cell locomotion, the early events in mating, and transport of food organisms along the cell surface, and possibly intracellular transport of certain organelles. Since surface motility is observed in association with cilia and flagella of algae, sea urchin embryos and cultured mammalian cells, it is likely that it serves an additional role beyond those already cited; this is likely to be the transport of precursors for the assembly and turnover of ciliary and flagellar membranes and axonemes. In the case of the Chlamydomonas flagellum, where surface motility has been most extensively studied, it appears that cross-linking of flagellar surface exposed proteins induces a transmembrane signaling pathway that activates machinery for moving flagellar membrane proteins in the plane of the flagellar membrane. This signaling pathway in vegetative Chlamydomonas reinhardtii appears to involve an influx of calcium, a rise in intraflagellar free calcium concentration and a change in the level of phosphorylation of specific membrane-matrix proteins. It is hypothesized that flagellar surface contact with a solid substrate (during gliding), a polystyrene microsphere or another flagellum (during mating) will all activate a signaling pathway similar to the one artificially activated by the use of monoclonal antibodies to flagellar membrane glycoproteins. A somewhat different signaling pathway, involving a transient rise in intracellular cAMP level, may be associated with the mating of Chlamydomonas gametes, which is initiated by flagellum-flagellum contact. The hypothesis that the widespread observation of microsphere movements on various ciliary and flagellar surfaces may reflect a mechanism normally utilized to transport axonemal and membrane subunits along the internal surface of the organelle membrane presents a paradox in that one would expect this to be a constitutive mechanism, not one necessarily activated by a signaling pathway.

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Ultrastructural, tomographic and confocal imaging of the chondrocyte primary cilium in situ

Jensen

Poole

McGlashan

et al. 2004

Cell Biology International

150

173

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Hyaline cartilage chondrocytes express one primary cilium per cell, but its function remains unknown. We examined the ultrastructure of chick embryo sternal chondrocyte cilia and their interaction with extracellular matrix molecules by transmission electron microscopy (TEM) and, for the first time, double-tilt electron tomography. Ciliary bending was also examined by confocal immunohistochemistry. Tomography and TEM showed the ciliary axoneme to interdigitate amongst collagen fibres and condensed proteoglycans. TEM also revealed the presence of electron-opaque particles in the proximal axoneme which may represent intraciliary-transport (ICT) particles. We observed a wide range of ciliary bending patterns. Some conformed to a heavy elastica model associated with shear stress. Others were acutely deformed, suggesting ciliary deflection by collagen fibres and proteoglycans with which the cilia make contact. We conclude that mechanical forces transmitted through these matrix macromolecules bend the primary cilium, identifying it as a potential mechanosensor involved in skeletal patterning and growth.

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Correlative light and high-voltage electron microscopy of primary (9 + 0) cilia in cultured kidney epithelial cells

Cited by 4 publications

References 3 publications

Heterotrimeric Kinesin-II Is Required for the Assembly of Motile 9+2 Ciliary Axonemes on Sea Urchin Embryos

Heterotrimeric Kinesin-II Is Required for the Assembly of Motile 9+2 Ciliary Axonemes on Sea Urchin Embryos

Directed movements of ciliary and flagellar membrane components: A review

Ultrastructural, tomographic and confocal imaging of the chondrocyte primary cilium in situ

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